Freenove Ultimate Starter Kit User Manual

193
Chapter 18 74HC595 & 7-segment display.
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If you want to display the decimal point, make the highest bit of each array become 0, which can be
implemented easily by num[i]&0x7f.
_shiftOut(dataPin,clockPin,MSBFIRST,num[i] & 0x7f);
Python Code 18.1.1 SevenSegmentDisplay
First observe the project result, and then analyze the code.
1. Use cd command to enter 18.1.1_SevenSegmentDisplay directory of Python code.
cd ~/Freenove_Ultimate_Starter_Kit_for_Raspberry_Pi/Code/Python_Code/18.1.1_SevenSegmentDisplay
2. Use python command to execute python code “SevenSegmentDisplay.py”.
python SevenSegmentDisplay.py
After the program is executed, SevenSegmentDisplay starts to display the character “0”- “F” successively.
The following is the program code:
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im port RPi. GPIO as GPIO
im port time
LSBFIRST = 1
MSBFIRST = 2
#define the pins connect to 74HC595
dataPin = 11 #DS Pin of 74HC595(Pin14)
latchPin = 13 #ST_CP Pin of 74HC595(Pin12)
clockPin = 15 #CH_CP Pin of 74HC595(Pin11)
#SevenSegmentDisplay display the character "0"- "F"successively
num = [0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e]
def setup():
GPIO. setmode(GPIO.BOARD) # Number GPIOs by its physical location
GPIO. setup(dataPin, GPIO. OUT)
GPIO. setup(latchPin, GPIO. OUT)
GPIO. setup(clockPin, GPIO. OUT)
def shiftOut(dPin,cPin,order,val):
for i in range(0,8):
GPIO.output(cPin,GPIO.LOW);
if(order == LSBFIRST):
GPIO.output(dPin,(0x01&(val>>i)==0x01) and GPIO.HIGH or GPIO.LOW)
elif(order == MSBFIRST):
GPIO.output(dPin,(0x80&(val<<i)==0x80) and GPIO.HIGH or GPIO.LOW)
GPIO.output(cPin,GPIO.HIGH);
def loop():
w hile Tr ue:
for i in range(0,len(num)):
GPIO.output(latchPin,GPIO.LOW)
shiftOut(dataPin,clockPin,MSBFIRST,num[i])#Output the figures and the highest
level is transfered preferentially.

Freenove Ultimate Starter Kit Specifications

General

Brand	Freenove
Model	Ultimate Starter Kit
Category	Single board computers
Language	English